[85] Rickets Flashcards

1
Q

What is rickets?

A

A condition that results in weak or soft bones in children

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2
Q

What is the most common cause of rickets?

A

Vitamin D deficiency

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3
Q

Where is vitamin D derived from?

A

Two main sources;

  • Synthesis from skin following exposure to UV light
  • Diet
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4
Q

What are the main functions of vitamin D?

A
  • Regulation of calcium and phosphate metabolism

- Functions in the immune system

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5
Q

What is the result of vitamin D being involved in the regulation of calcium and phosphate metabolism?

A

Makes it essential for bone health

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6
Q

What happens if vitamin D is not supplied in adequate levels in childhood?

A

Rickets will develop

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7
Q

What does vitamin D deficiency usually result from?

A
  • Inadequate UVB exposure
  • Deficient intake
  • Defective metabolism of vitamin D
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8
Q

What effect does a vitamin D deficiency have on calcium?

A

It causes a low serum calcium

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9
Q

What is the result of a low serum calcium?

A

It triggers the secretion of PTH

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10
Q

What effect does an increased secretion of PTH have?

A
  • Normalises calcium, but demineralises bone

- Causes loss of renal phosphate, and subsequently low serum phosphate levels

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11
Q

What is the result of low serum phosphate levels?

A

It further reduces the potential for bone calcification

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12
Q

What are the categories of causes of rickets?

A
  • Nutritional (primary) rickets
  • Intestinal malabsorption
  • Problems with 25-hydroxyvitamin D
  • Problems with 1,25-dihydroxyvitamin D
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13
Q

What are the risk factors for primary rickets?

A
  • Living in northern latitudes
  • Dark skin
  • Decreased exposure to sunlight
  • Maternal vitamin D deficiency
  • Diets low in calcium, phosphorus, and vitamin D
  • Macrobiotic, strict vegan diets
  • Prolonged parenteral nutrition in infancy
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14
Q

Give an example of when the diet may be low in calcium, phosphorus, and vitamin D

A

Exclusive breastfeeding into late infancy

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15
Q

What are the causes of intestinal malabsorption?

A
  • Small bowel enteropathy
  • Pancreatic insufficiency
  • Cholestatic liver disease
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16
Q

Give an example of a small bowel enteropathy that can lead to rickets

A

Coeliac disease

17
Q

Give an example of a cause of pancreatic insufficiency that can lead to rickets

A

Cystic fibrosis

18
Q

What are the causes of problems with 25-hydroxyvitamin D?

A
  • Defective production
  • Increased metabolism
  • Defective production
19
Q

Give a cause of defective production of 25-hydroxyvitamin D

A

Chronic liver disease

20
Q

Give a cause of increased metabolism of 25-hydroxyvitamin D

A

Enzyme induction by anticonvulsants

21
Q

What are the causes of defective production of 1,25-dihydroxyvitamin D

A
  • CKD
  • Fanconi syndrome
  • Inherited disorders
22
Q

How can rickets present?

A
  • Craniotabes
  • Rachitic rosary
  • Widened wrists and ankles
  • Harrison’s sulcus
  • Poor growth/short stature
  • Delayed dentition
  • Bowing of weight-bearing bones
  • Hypotonia
  • Seizures
  • Cardiomyopathy/heart failure
23
Q

What are craniotabes?

A

Softening or thinning of the skull in infants and children, mostly seen in occipital and parietal bones

24
Q

How do craniotabes present?

A

The bones are soft, and when pressure is applied they will collapse underneath it

25
Q

What is rachitic rosary?

A

Expansion of the anterior rib ends at the costochondral junctions

26
Q

What is Harrison’s sulcus?

A

A horizontal depression on the lower chest corresponding to the attachment of the softened ribs with the diaphragm

27
Q

What investigations should be done in rickets?

A
  • Bloods

- X-ray of wrist joints

28
Q

What may be found on bloods in rickets?

A
  • Serum calcium low or normal
  • Phosphorus low
  • Plasma alkaline phosphatase activity high
  • 25-hydroxyvitamin D may be low
  • PTH elevated
29
Q

What does the x-ray of the wrist joint show in rickets?

A

Cupping and fraying of the metaphyses, and a widened epiphyseal plate

30
Q

What is an important differential diagnosis for rickets?

A

Bone fracture, can be mistaken for non-accidental injury

31
Q

How is nutritional rickets managed?

A
  • Advice about balanced diet, and foods rich in vitamin D
  • Correction of pre-disposing risk factors
  • Daily administration of vitamin D3 (cholecalciferol)
32
Q

Give 2 examples of foods rich in vitamin D

A
  • Oily fish

- Egg yolk

33
Q

How long does healing take after management for rickets?

A

2-4 weeks

34
Q

What shows healing in rickets?

A
  • Lowering of alkaline phosphatase
  • Increasing vitamin D levels
  • Healing on bone x-rays
35
Q

How long does complete reversal of bony deformities take in rickets?

A

May take years

36
Q

What are the potential complications of rickets?

A
  • Bone fractures
  • Muscle spasms
  • Abnormally curved spine
  • Intellectual disability